267 research outputs found
cis-Bis[(1-adamantylmethÂyl)amine-ÎșN]Âdichloridoplatinum(II) N,N-dimethylÂformamide solvate
The asymmetric unit of the title compound {systematic name: cis-dichloridobis[(3,7-dimethylbicycloÂ[3.3.1]non-1-ylmethÂyl)Âamine-ÎșN]platinum(II) N,N-dimethylÂformamide solvate}, [PtCl2(C11H19N)2]·C3H7NO, consists of two metrically similar Pt complexes and two dimethylÂformamide solvent molÂecules. Each PtII center is coordinated by the amine groups of two (1-adamantylmethÂyl)amine ligands and two Cl atoms in a cis-square-planar arrangement. The PtII centers lie slightly outside [0.031â
(4) and 0.038â
(4)â
Ă
] the coordination planes. The NâPtâN and ClâPtâCl angles [92.1â
(4)â92.30â
(11)°] are slightly more open than the NâPtâCl angles [87.3â
(3)â88.3â
(3)°]. NâHâŻO and NâHâŻCl interÂmolecular hydrogen bonds are observed, forming two discrete pairs of complexes and solvent molÂecules
RÎle des conditions pédoclimatiques sur la présence d'une savane en milieu forestier tropical africain : cas de la savane de Dabou (CÎte-d'Ivoire)
La rĂ©gion de Dabou a longtemps Ă©tĂ© caractĂ©risĂ©e par la prĂ©sence d'une savane, vĂ©gĂ©tation inhabituelle dans cette zone subĂ©quatoriale humide Ă forĂȘt sempervirente. Les Ă©tudes rĂ©alisĂ©es derniĂšrement montrent que cette rĂ©gion se distingue non seulement par sa vĂ©gĂ©tation, mais Ă©galement par une organisation de la couverture pĂ©dologique en rapport avec un paysage (modelĂ©, rĂ©seau hydrographique) caractĂ©ristique de zones plus sĂšches. Le facteur permettant d'expliquer le maintien de la savane jusqu'Ă une Ă©poque rĂ©cente est avant tout d'ordre pĂ©doclimatique. (RĂ©sumĂ© d'auteur
SynthÚse et caractérisation de complexes de technétium(V) et de rhénium(V) contenant des acides aminés et des dipeptides
ThÚse numérisée par la Direction des bibliothÚques de l'Université de Montréal
Ethylenediamine- and propylenediaminediacetic acid derivatives as ligands for the "fac-[M(CO)3]+" core (M = Re, 99mTc)
The reaction of Re(CO)5Cl with o- or p-N-(nitrophenyl)ethylenediaminediacetic acid (H2L1, H2L2) and o- or p-N-(nitrophenyl)propylenediaminediacetic acid (H2L3, H2L4) in methanol leads to the formation of stable anionic [Et3NH][Re(CO)3(L)]·H2O complexes 1-4. These compounds have been characterized by means of IR, mass spectrometry, elemental analysis, NMR and conductimetry, as well as X-ray crystallography for 2 and 3. The [Re(CO)3]+ moiety is coordinated via the nitrogen of the iminodiacetic acid unit and two oxygens of monodentate carboxylate groups. In each case, the nitro group of the aromatic ring remains uncoordinated. The analogous technetium-99m complexes 1' and 3' were also prepared quantitatively by the reaction of H2L1 and H2L3, respectively, with the fac-[99mTc(CO)3(H2O)3]+ precursor in ethanol. The corresponding Re and 99mTc compounds were shown to possess the same structure by means of HPLC studies. The high affinity of these ligands for the Tc(I) or Re(I) core, coupled with the easiness of their derivatization (by reduction of the nitro group in amino group), implies that the utilization of this ligand system to develop target-specific radiopharmaceuticals for diagnosis and therapy is promising
Dendrochronological approach to the radial growth of okoume (Congo)
La croissance radiale de 4 sections d'okoumĂ© du Congo provenant de 4 arbres diffĂ©rents est analysĂ©e. La prĂ©sence dans la rĂ©gion d'au moins une saison sĂšche marquĂ©e permet de dĂ©finir des cernes de croissance annuels. Ils sont mesurĂ©s et les courbes des largeurs de cernes sont confrontĂ©es de maniĂšre graphique afin de vĂ©rifier que l'annĂ©e de formation attribuĂ©e Ă chaque cerne est exacte (interdatation). Le synchronisme est mauvais lorsque les courbes appartiennent Ă des arbres diffĂ©rents. Pour lever le doute quant Ă la validitĂ© de la dĂ©limitation des cernes annuels, une confrontation avec les enregistrements pluviomĂ©triques de Pointe Noire est tentĂ©e. Le rĂ©sultat du test est positif et les limites de cernes Ă©tablies au dĂ©but de l'Ă©tude sont maintenues. L'approche dendrochronologique sur une espĂšce telle que l'okoumĂ© est donc possible mais une vĂ©rification de l'interdatation par confrontation avec des donnĂ©es climatologiuqes est indispensable. Ce type d'approche conduisant Ă une datation absolue des cernes peut ĂȘtre d'un grand intĂ©rĂȘt en Ă©cologie tropicale : elle permet en particulier de replacer les analyses biogĂ©ochimiques des cernes dans un cadre chronologique exact, ou encore d'apprĂ©cier la vitesse de progression des lisiĂšres forestiĂšres. (RĂ©sumĂ© d'auteur
Adaptation of environmental data to national and sectorial context: application for reinforcing steel sold on the French market
Purpose: Environmental data for steel products are generally proposed at a continental or a global scale. The question we are tackling here is: does the fact that steel as a global market necessarily reduces the need for national data? Methods: In this study, the environmental impact of reinforcing steel sold in France is evaluated. To do so, a specific environmental inventory is adapted from Ecoinvent database. CML method is used for impact calculation and both methods "recycled contentâ as well as "end of life recycling approachâ are tested. Results and discussion: This study shows that there is a specificity of reinforcing steel products sold in France compared to European value. It is due to the fact that reinforcing steel is mainly made with recycled steel as the market growth for construction product in France is limited allowing a very high recycled content. This result is not sensitive neither to the allocation method used for recycling (cut-off approach or system expansion) nor to transport distance and electricity country mix used. Conclusions: The result of this study can be used with confidence in every construction site work located on the French territory. Furthermore, the present study advocates for an adaptation of global database to local context defined by a specific industrial sector and a geographic region even for product such as steel that may be considered as a first approximation as a global produc
On the interaction of acetone with electrophilic metallocavitands having extended cavities
We report the synthesis and characterization of tantalumâboronate trimetallic clusters of general formula {[Cp*Ta]3(ÎŒ2-RB(O)2)3(ÎŒ2-OH)(ÎŒ2-O)2(ÎŒ3-OH)} (R= 4-(C6H5)(C6H4) (Ta3-4Ph), 4-(C6H5O)(C6H4) (Ta3-4OPh), 4-(C7H7O)(C6H4) (Ta3-4OBn), 4-(C8H5)(C6H4) (Ta3-4PhEt), and 4-(C12H7)(C6H4) (Ta3-4Napht)). All complexes have been characterized by NMR spectroscopy and X-ray diffraction. The trimetallic species feature a large Lewis acid type cavity allowing for substrate binding in both the solid and the liquid state using a unique electrostatic interaction and a hydrogen bond. ÎH° and ÎS° values for association of acetone with the complexes vary between â2.0 and â4.1 kcal·molâ1 and â3 and 2 cal·molâ1·Kâ1, respectively, showing weaker binding than smaller cavitands of the same type. The barrier for acetone exchange at equilibrium is similar for all complexes, and ÎH⥠values vary between 8.2 and 11.4 kcal·molâ1
Genetic Variation in LPA, Calcific Aortic Valve Stenosis in Patients Undergoing Cardiac Surgery, and Familial Risk of Aortic Valve Microcalcification.
IMPORTANCE: Genetic variants at the LPA locus are associated with both calcific aortic valve stenosis (CAVS) and coronary artery disease (CAD). Whether these variants are associated with CAVS in patients with CAD vs those without CAD is unknown. OBJECTIVE: To study the associations of LPA variants with CAVS in a cohort of patients undergoing heart surgery and LPA with CAVS in patients with CAD vs those without CAD and to determine whether first-degree relatives of patients with CAVS and high lipoprotein(a) (Lp[a]) levels showed evidence of aortic valve microcalcification. DESIGN, SETTING, AND PARTICIPANTS: This genetic association study included patients undergoing cardiac surgery from the Genome-Wide Association Study on Calcific Aortic Valve Stenosis in Quebec (QUEBEC-CAVS) study and patients with CAD, patients without CAD, and control participants from 6 genetic association studies: the UK Biobank, the European Prospective Investigation of Cancer (EPIC)-Norfolk, and Genetic Epidemiology Research on Aging (GERA) studies and 3 French cohorts. In addition, a family study included first-degree relatives of patients with CAVS. Data were collected from January 1993 to September 2018, and analysis was completed from September 2017 to September 2018. EXPOSURES: Case-control studies. MAIN OUTCOMES AND MEASURES: Presence of CAVS according to a weighted genetic risk score based on 3 common Lp(a)-raising variants and aortic valve microcalcification, defined as the mean tissue to background ratio of 1.25 or more, measured by fluorine 18-labeled sodium fluoride positron emission tomography/computed tomography. RESULTS: This study included 1009 individuals undergoing cardiac surgery and 1017 control participants in the QUEBEC-CAVS cohort; 3258 individuals with CAVS and CAD, 41âŻ100 controls with CAD, 2069 individuals with CAVS without CAD, and 380âŻ075 control participants without CAD in the UK Biobank, EPIC-Norfolk, and GERA studies and 3 French cohorts combined; and 33 first-degree relatives of 17 patients with CAVS and high Lp(a) levels (â„60 mg/dL) and 23 control participants with normal Lp(a) levels (<60 mg/dL). In the QUEBEC-CAVS study, each SD increase of the genetic risk score was associated with a higher risk of CAVS (odds ratio [OR], 1.35 [95% CI, 1.10-1.66]; Pâ=â.003). Each SD increase of the genetic risk score was associated with a higher risk of CAVS in patients with CAD (OR, 1.30 [95% CI, 1.20-1.42]; Pâ<â.001) and without CAD (OR, 1.33 [95% CI, 1.14-1.55]; Pâ<â.001). The percentage of individuals with a tissue to background ratio of 1.25 or more or CAVS was higher in first-degree relatives of patients with CAVS and high Lp(a) (16 of 33 [49%]) than control participants (3 of 23 [13%]; Pâ=â.006). CONCLUSIONS AND RELEVANCE: In this study, a genetically elevated Lp(a) level was associated with CAVS independently of the presence of CAD. These findings support further research on the potential usefulness of Lp(a) cascade screening in CAVS
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